Shock-cushioning structure

ABSTRACT

A small-volumed shock-cushioning structure SA of the present invention guarantees absorption of shocks of different magnitudes associated with two different states of a hard disk, and thereby to effectively protect the hard disk from the shocks of different magnitudes. The shock-cushioning structure SA includes a first shock-cushioning material CAL having a first stress-strain characteristic AL with a first effective cushioning stress, and a second shock-cushioning material CAH having a second stress-strain characteristic AH with a second effective cushioning stress greater than the first effective cushioning stress of the first stress-strain characteristic AL.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a shock-cushioning structure forholding a device susceptible to externally applied shocks and protectingthe device by absorbing shocks applied thereto. More particularly, thepresent invention relates to a shock-cushioning structure used forprotecting a device vulnerable to shocks, e.g., a hard disk driveincorporated in a notebook computer.

2. Description of the Background Art

In recent years, a wide range of information processing apparatuses,including a notebook computer, have become lighter, smaller, andthinner, while achieving higher performance and larger capacity. Inorder to satisfy the needs of higher performance and larger capacity, aninformation processing apparatus has incorporated therein a high-densityand high-precision hard disk drive (hereinafter, simply referred to as a“hard disk”) as a storage device. In order to extend storage capacity orprotect security of stored information, the hard disk might befrequently attached to or detached from the information processingapparatus. Moreover, the detached hard disk might be carried by itselfor kept separate from the information processing apparatus.

Accordingly, in the case of carrying the information processingapparatus, shock and vibration transmitted into the informationprocessing apparatus might damage the hard disk held within theinformation processing apparatus. Further, in the case where the harddisk is carried by itself, rather than held in the informationprocessing apparatus, the hard disk might directly undergo shock andvibration, and therefore might be damaged more severely. Furthermore,even if the hard disk is kept in storage, the hard disk might be damageddue to unexpected shock and vibration, depending on the circumstance inwhich it is kept in storage.

In order to avoid the problems as described above, various contrivancesare employed for minimizing shock and vibration caused to the hard disk,thereby preventing the hard disk from being damaged regardless ofwhether the hard disk is held in the information processing apparatus.

Because of the ease of portability, the information processing apparatusas described above is widely used indoor and outdoor. In such usage, itis variable as to where and how the information processing apparatus isused. Accordingly, the information processing apparatus might be bumpedby mistake against a hard object during carriage, might be roughlyplaced on a table or the like, or might be dropped from the table whenit is used or not. In such a situation, the hard disk held inside as astorage device might be damaged by shock and/or vibration transmittedinto the information processing apparatus.

A variety of shock-cushioning structures have been proposed forabsorbing externally applied shock and/or vibration as described above,thereby protecting the hard disk. Although the proposed shock-cushioningstructures are provided in a variety of shapes, they have a common basicstructure in that a jacket, which is formed by an elastic materialfunctioning as a cushion, covers the outer edge of the hard disk, anddeforms itself in response to externally applied shocks, therebyabsorbing and buffering the shocks.

The above-mentioned common structure of conventional shock-cushioningstructures and an information processing apparatus employing such acommon structure are described below with reference to FIGS. 14, 15, 16,and 17.

FIG. 14 shows an information processing apparatus having incorporatedtherein a hard disk held by a conventional and common shock-cushioningstructure. In FIG. 14, for the sake of illustration, a hard disk storagesection 1 c of an information processing apparatus Dpp is shown with itsflip-up lid L open. The information processing apparatus Dpp includes akeyboard 4 provided on the rear side of a housing 1, and the storagesection 1 c provided on the front side for storing detachable elements,such as a hard disk. The storage section 1 c stores a main circuit board2 and a hard disk unit SU in which a hard disk is held by ashock-cushioning structure. Note that the hard disk unit SU is connectedto the main circuit board 2 via a signal cable 6 in a freely movablemanner. The flip-up lid L is provided as an upper face of the storagesection 1 c. Further, a display section 5 is provided on an upper edgeof the housing 1 in such a manner as to be freely open and closed.

FIG. 15 shows a structure of the hard disk unit SU. The hard disk unitSU includes a hard disk 3, a shock-cushioning structure 51, and a cover52. The shock-cushioning structure 51 is made of a low-rigidity andlow-repulsive material, and has a box-like shape with a recess portion51 c adapted to the shape of the hard disk 3. The cover 52 is made ofthe same material as the shock-cushioning structure 51, and has a flatplate-like shape.

In the hard disk unit SU, the hard disk 3 is accommodated in the recessportion 51 c of the shock-cushioning structure 51, and the cover 52 isfitted into the recess portion 51 c so as to hold the hard disk 3. Notethat the signal cable 6 of the hard disk 3 extends out of the hard diskunit SU from between the shock-cushioning structure 51 and the cover 52,and is connected to the main circuit board 2 as described above.

FIG. 16 shows a state of the hard disk unit SU when the informationprocessing apparatus Dpp undergoes shock from the side. If the shock isapplied to the housing 1 of the information processing apparatus Dppfrom a direction of arrow Fa, an impact force is generated so as to movethe hard disk 3 along an Fr direction which is opposite to the Fadirection. However, the shock-cushioning structure 51 and the cover 52are made of a low-rigidity and low-repulsive material, and thereforewhen the hard disk 3 moves along the Fr direction, the shock-cushioningstructure 51 deforms itself in the vicinity of a side face 3 a of thehard disk 3, thereby absorbing the impact force acting on the hard disk3. Such deformation of the shock-cushioning structure prevents the harddisk 3 from being damaged by the shock.

Note that when implementing capacity extension or security protection,the hard disk unit SU may be detached from the housing 1 or only thehard disk 3 may be detached from the shock-cushioning structure 51 andthe cover 52.

As described above, in the conventional shock-cushioning structure, theshock-cushioning structure 51 deforms itself in a portion, which is incontact with the hard disk 3 moved due to shock, thereby absorbing animpact force acting on the hard disk 3 at a prescribed rate. However,the impact force to be withstood by the hard disk 3 varies depending onits operation status. Specifically, in the case where the informationprocessing apparatus is in use, a shock-withstanding capability of thehard disk 3 is different between when the hard disk 3 is in operationand when the hard disk 3 is not in operation. When the hard disk 3 isnot in operation, a magnetic head is on standby on a non-recordingsurface, and the hard disk 3 is able to withstand shock even if arelatively large impact force is applied thereto. On the other hand,when the hard disk 3 is in operation, the magnetic head is located abovea platter, and the hard disk 3 might be damaged even by a small shock.Accordingly, the magnitude of an impact force to be absorbed by theshock-cushioning structure 51 is considerably different between when thehard disk 3 is in operation and when the hard disk 3 is not inoperation.

Referring to FIG. 17, descriptions are provided with respect to themagnitude of an impact force to be absorbed and a required shockabsorption characteristic of the shock-cushioning structure. In FIG. 17,the horizontal axis indicates height of fall of a hard diskcorresponding to shock applied to the hard disk, and the vertical axisindicates a shock value G at which the safety of the hard disk isguaranteed. Curve L1 indicates variations of the shock value at whichthe safety of the hard disk not in operation is guaranteed, and curve L2indicates variations of the shock value at which the safety of the harddisk in operation is guaranteed.

Here, it is assumed that the hard disk in operation is guaranteed towithstand a shock caused in the case of a fall from a height of up to 60centimeters (cm) and the hard disk not in operation is guaranteed towithstand a shock caused in the case of a fall from a height of up to 80cm. It is appreciated from FIG. 17 that a shock caused in the case of afall from a height of 60 cm is approximately 200 G, and a shock causedin the case of a fall from a height of 80 cm is approximately 700 G.

Accordingly, a value of shock to be absorbed when the hard disk is inoperation is approximately 200 G, a value of shock to be absorbed whenthe hard disk is not in operation is approximately 700 G, and there is aconsiderable difference between the values of shock to be absorbed. Theshock-cushioning structure deforms itself to absorb shock, and thereforeif the ratio of absorption deformation to shock is constant, theshock-cushioning structure is required to shrink and deform itself inrelation to the magnitude of the shock. However, in order to realize alighter, smaller, and thinner information processing apparatus, it isnecessary to reduce the size of the shock-cushioning structure forprotecting the hard disk from the shock, so that the amount of shrinkageand deformation is restricted. Under such a circumstance where theamount of shrinkage and deformation is restricted, it is necessary toreduce the amount of deformation to shock in order to absorb a largeshock which is required to be reliably absorbed when the hard disk isnot in operation. In this case, it is necessary to select a hardershock-cushioning material. However, a hard shock-cushioning material forabsorbing a large shock reflects a small shock equivalent to a shockwhich is required to be reliably absorbed when the hard disk is inoperation, and therefore the small shockwave cannot be satisfactorilyabsorbed. Accordingly, if a space for accommodating the conventionalshock-cushioning structure is limited, it is not possible to effectivelyprotect the hard disk from shocks of two different shock values.

SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to provide asmall-volumed shock-cushioning structure which guarantees absorption ofshocks of different magnitudes associated with two different states of ahard disk, and thereby to effectively protect the hard disk from theshocks of different magnitudes.

The present invention has the following features to attain the objectmentioned above.

A first aspect of the present invention is directed to ashock-cushioning structure formed by first and second shock-cushioningmaterials which are strained under impact stress to absorb the impactstress. The first shock-cushioning material has a first stress-straincharacteristic with a first effective cushioning stress, and the secondshock-cushioning material has a second stress-strain characteristic witha second effective cushioning stress greater than the first effectivecushioning stress of the first stress-strain characteristic.

Thus, despite its small volume, the shock-cushioning structure of thepresent invention is able to guarantees absorption of shocks ofdifferent magnitudes associated with two different states of the harddisk, and thereby to effectively protect the hard disk from the shocksof different magnitudes.

These and other objects, features, aspects and advantages of the presentinvention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a configuration of ashock-cushioning structure according to a first embodiment of thepresent invention;

FIG. 2 is a graph showing a shock absorption characteristic of theshock-cushioning structure shown in FIG. 1;

FIG. 3 is a perspective view showing a configuration of ashock-cushioning structure according to a second embodiment of thepresent invention;

FIG. 4 is a graph showing a shock absorption characteristic of theshock-cushioning structure shown in FIG. 3;

FIG. 5 is a perspective view showing a configuration of ashock-cushioning structure according to a third embodiment of thepresent invention;

FIG. 6 is a graph showing a shock absorption characteristic of theshock-cushioning structure shown in FIG. 5;

FIG. 7 is a perspective view showing a configuration of ashock-cushioning structure according to a fourth embodiment of thepresent invention;

FIG. 8 is a perspective view showing a configuration of ashock-cushioning structure according to a fifth embodiment of thepresent invention;

FIG. 9 is a graph used for explaining a basic feature of ashock-cushioning structure of the present invention;

FIG. 10 is a view used for explaining how the shock-cushioning structureshown in FIG. 3 is applied;

FIG. 11 is a view used for explaining how a variation of theshock-cushioning structure shown in FIG. 3 is applied;

FIG. 12 is a view used for explaining how a variation of theshock-cushioning structure shown in FIG. 8 is applied;

FIG. 13 is a view used for explaining how a combination ofshock-cushioning structures of the present invention is used;

FIG. 14 is a perspective view showing an information processingapparatus having incorporated therein a hard disk held by a conventionalshock-cushioning structure;

FIG. 15 is an exploded view showing the shock-cushioning structure andthe hard disk shown in FIG. 14;

FIG. 16 is a schematic view showing a state where shock applied to ahard disk is absorbed by the shock-cushioning structure shown in FIG.14; and

FIG. 17 is a graph showing shock absorption characteristics of ashock-cushioning structure in relation to two shocks to be absorbed.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Firstly, a basic feature of a shock-cushioning structure of the presentinvention is described with reference to FIG. 9. In FIG. 9, the verticalaxis indicates impact stress (Kfg/mm²) applied to a shock absorptioncushioning material, the horizontal axis indicates the amount (%) ofstrain of the shock absorption cushioning material corresponding to theimpact stress, curve CL indicates a stress-strain characteristic of alow impact force absorption cushioning material, and curve CH indicatesa stress-strain characteristic of a high impact force absorptioncushioning material. From FIG. 9, it is appreciated that the low impactforce absorption cushioning material is considerably strained even by alow impact stress, thereby protecting a hard disk in operation from asmall shock, while the high impact force absorption cushioning materialis merely slightly strained even by a high impact stress, therebyprotecting a hard disk not in operation from a large shock.

In general, it is known that an ideal cushioning material or structureunder impact stress is characteristically deformed with a strain of upto about 70%. In the following descriptions, the range of the strain ofup to about 70% is referred to as an “effective shock cushioning rangeRa” of the cushioning material, and the range of impact stress, whichcan be absorbed in the effective shock cushioning range Ra, is referredto as an “effective cushioning stress Sa”. In FIG. 9, the effectivecushioning stress Sa of a soft shock absorbing material AL having a lowshock absorption characteristic CL is about 0.04 kgf/mm², and theeffective cushioning stress Sa of a hard shock absorbing material AHhaving a high shock absorption characteristic CH is about 0.19 kgf/mm².Note that the effective cushioning stresses Sa of the soft and hardshock absorbing materials AL and AH are respectively referred to belowas a “low effective cushioning stress SaL” and a “high effectivecushioning stress SaH”.

However, it is apparent that the soft shock absorbing material AL issuitable for an impact stress of about 0.04 kgf/mm² or less.Accordingly, the present invention provides a shock-cushioning structureby combining the soft and hard shock absorbing materials AL and AH, suchthat the soft shock absorbing material AL responds to a small shockapplied to the hard disk in operation, while the hard shock absorbingmaterial AH responds to a larger shock applied to the hard disk inoperation.

First Embodiment

A shock-cushioning structure according to a first embodiment of thepresent invention is described below with reference to FIGS. 1 and 2. InFIG. 1, arrow Fg indicates a direction of an impact stress applied to ashock-cushioning structure SA1. The shock-cushioning structure SA1includes a solid CALL formed by the soft shock absorbing material AL anda solid CAH1 formed by the hard shock absorbing material AH. In FIG. 2,two dotted curves indicate the low and high shock absorptioncharacteristics CL and CH as shown in FIG. 9, and solid line C1indicates a shock absorption characteristic of the shock-cushioningstructure SA1.

Specifically, in the shock-cushioning structure SA1, the soft shockabsorbing material AL having the low shock absorption characteristic CLresponds to an impact stress of about 0.04 Kgf/mm² or less, and the softshock absorbing material AH having the high shock absorptioncharacteristic CH responds to an impact stress of more than about 0.04Kgf/mm² but not more than 0.19 Kgf/mm². Note that at a strain of about55%, the shock absorption characteristic C1 of the shock-cushioningstructure SA1 is abruptly shifted from the low shock absorptioncharacteristic CL to the high shock absorption characteristic CH. Thereason for this is that the solids CAL1 and CAH1 are connected in aplane. Specifically, the shock-cushioning structure SA1 is configuredsuch that a shock of up to 0.04 Kgf/mm² is flexibly received by thesolid CAL1, while a greater shock is securely received by the solidCAH1.

Note that in a direction substantially parallel to the impact stressdirection Fg shown in FIG. 1, a thickness TL1 of the solid CAL1 and athickness TH1 of the solid CAH1 are suitably determined based on thesize of a space in which the shock-cushioning structure SA1 isaccommodated and the amounts of strains of the solids CAH1 and CAL1. Inthe following descriptions, the term “shock absorption characteristictransition range RT” is used to refer to a range around a strain ofabout 55% where a shock absorption characteristic C of ashock-cushioning structure SA is shifted from the low shock absorptioncharacteristic CL to the high shock absorption characteristic CH. Notethat a thickness T of the shock-cushioning structure SA1 is equivalentto the sum of the thicknesses TL1 and TH1.

Second Embodiment

A shock-cushioning structure according to a second embodiment of thepresent invention is described below with reference to FIGS. 3 and 4. InFIG. 3, a shock-cushioning structure SA2 includes a solid CAL2 formed bythe soft shock absorbing material AL and a solid CAH2 formed by the hardshock absorbing material AH. The solid CAH2 is similar in size to theabove-described solid CAH1. Both of the solids CAL2 and CAH2 are formedin a wedge-like shape. A length TL2 a of a shorter side of the solidCAL2 and a length TL2 b of a longer side of the solid CAL2 arepreferably represented by the following expressions (1) and (2),respectively.TL2a=TL1−TH1/2   (1)TL2b=TL1+TH1/2   (2)

A length TH2 a of a longer side of the solid CAH2 and a length TH2 b ofa shorter side of the solid CAH2 are preferably represented by thefollowing expressions (3) and (4), respectively.TH2a=T−TL2a   (3)TH2b=T−TL2b   (4)

FIG. 4 shows a shock absorption characteristic C2 of theshock-cushioning structure SA2. In comparison with the shock absorptioncharacteristic C1 of the shock-cushioning structure SA1 according to thefirst embodiment, the shock absorption characteristic C2 of theshock-cushioning structure SA2 varies moderately in the shock absorptioncharacteristic transition range RT. Note that in order to cause theshock absorption characteristic C2 to vary moderately in the shockabsorption characteristic transition range RT, the relationshipsrepresented by the above expressions (1), (2), (3), and (4) do notnecessarily require to be satisfied, and the shock absorptioncharacteristic C2 can be suitably determined based on a stress-straincharacteristic and a shock absorption characteristic transition point ofeach of the soft and hard shock absorbing materials.

Third Embodiment

A shock-cushioning structure according to a third embodiment of thepresent invention is described below with reference to FIGS. 5 and 6. InFIG. 5, similar to the shock-cushioning structure SA2, ashock-cushioning structure SA3 includes a solid CAL3 formed by the softshock absorbing material AL and a solid CAH3 formed by the hard shockabsorbing material AH. The solids CAH3 and CAL3 have curved connectionsurfaces. Specifically, the connection surface of the solid CAH3 isconcave, and the connection surface of the solid CAL3 is convex.

A length TL3 a of a shorter side of the solid CAL3 and a length TL3 b ofa longer side of the solid CAL3 are preferably represented by thefollowing expressions (5) and (6), respectively.TL3a≦TL1−TH1/2   (5)TL3b=TL1+TH1/2   (6)

A length TH3 a of a longer side of the solid CAL3 and a length TH3 b ofa shorter side of the solid CAH3 are preferably represented by thefollowing expressions (7) and (8) ,respectively.TH3a=T−TL3a   (7)TH3b=T−TL3b   (8)

FIG. 6 shows a shock absorption characteristic C3 of theshock-cushioning structure SA3. In comparison with the shock absorptioncharacteristic C2 of the shock-cushioning structure SA2 according to thesecond embodiment, the shock absorption characteristic C3 of theshock-cushioning structure SA3 is shifted more moderately from the lowshock absorption characteristic CL to the high shock absorptioncharacteristic CH. Note that in order to obtain the shock absorptioncharacteristic C3, the relationships represented by the aboveexpressions (5), (6), (7), and (8) do not necessarily require to besatisfied, and the shock absorption characteristic C3 can be suitablydetermined based on a stress-strain characteristic and a shockabsorption characteristic transition point of each of the soft and hardshock absorbing materials.

Fourth And Fifth Embodiments

Shock-cushioning structures according to fourth and fifth embodiments ofthe present invention are described below with reference to FIGS. 7 and8.

As shown in FIG. 7, a shock-cushioning structure SA4 according to thefourth embodiment is configured such that a solid CAL4 formed by thesoft shock absorbing material AL is parallel to and in contact with asolid CAH3 r formed by the hard shock absorbing material AH. Preferably,the solid CAL4 is equivalent in size to the shock-cushioning structureSA1, and the solid CAH3 r has a shape similar to that of the solid CAH3.With this configuration, the solid CAL4 formed by the soft shockabsorbing material AL and the solid CAH3 r formed by the hard shockabsorbing material are simultaneously strained in the shock absorptioncharacteristic transition range RT, whereby it is possible to obtain asmoother shock absorption characteristic C4 (not shown).

In FIG. 8, a shock-cushioning structure SA5 according to the fifthembodiment includes a solid CAL5 formed by the soft shock absorbingmaterial AL and a solid CAH5 formed by the hard shock absorbing materialAH. The solid CAL5 has vertical trapezoidal faces in the impact stressdirection Fg. The solid CAH5 also has vertical trapezoidal faces in theimpact stress direction Fg. As a result, the shock-cushioning structureSA5 has a smoother shock absorption characteristic C5 (not shown).

Referring to FIGS. 10, 11, 12, 13, and 14, a brief description is givenbelow with respect to how the shock-cushioning structure of the presentinvention is applied. Firstly, an example of using the shock-cushioningstructure SA2 to absorb a shock applied to the hard disk 3 is describedwith reference to FIG. 10. In FIG. 10, the shock-cushioning structureSA2 is applied such that the solid CAH2 formed by the hard shockabsorbing material AH is in contact with the hard disk 3, and the solidCAL2 formed by the soft shock absorbing material AL is in contact withthe housing of a notebook personal computer, for example. Thisapplication of the shock-cushioning structure SA2 is suitable forcushioning the shock applied to the hard disk 3 by catching the harddisk 3 using an area smaller than a catching area of the cushioningmaterial (i.e., one entire surface of the shock-cushioning structureSA2). Since the solid CAH2 is hard, even if the hard disk 3 is caught byonly a portion of the solid CAH2, the solid CAH2 is able to deformitself entirely to absorb an impact of the hard disk 3 on the solidCAH2. The solid CAL2 supports the solid CAH2 by its entire connectionsurface with the solid CAH2, and therefore each of the solids CAH2 andCAL2 can be used to full advantage to cushion a shock applied to thehard disk 3. Accordingly, it is possible to minimize a difference indegree of shock which occurs at the connection surface between thesolids CAH2 and CAL2, thereby obtaining a smooth two-phase shockabsorption capability.

On the other hand, in the case where the shock-cushioning structure SA2is applied such that the solid CAL2 is in contact with the hard disk 3,and the solid CAH2 is in contact with the housing of the notebookpersonal computer, the solid CAL2 is partially deformed by the hard disk3 with which a portion of the solid CAL2 is in contact. As a result, ashock cannot be transmitted to the solid CAH2 through the entireconnection surface between the solids CAL2 and CAH2 but through aportion of the connection surface. Accordingly, another shock occurs atthe connection surface between the solids CAL2 and CAH2. Since the solidCAL2 is a soft shock absorbing material, the magnitude of shock whichcan be absorbed by the solid CAL2 is smaller than the magnitude of shockwhich can be absorbed by the solid CAH2. Moreover, partial deformationof the solid CAL2 reduces the shock absorption capability of the solidCAL2. That is, the solid CAL2 cannot make full use of its shockabsorption capability. Further, the entire shock-cushioning structureSA2 cannot entirely make full use of its shock absorption capability.

Similar to FIG. 10, FIG. 11 is used for explaining an example of usingthe shock-cushioning structure SA of the present invention to absorb ashock applied to the hard disk 3. In this example, a solid SCH formed bya shock absorbing material harder than the solid CAH2 is provided on thesolid CAH2 of the shock-cushioning structure SA2 shown in FIG. 10. Thatis, the solid SCH is in contact with the hard disk 3. Specifically, thesolid SCH is connected to the solid CAH2 which is connected to the solidCAL2, thereby forming a shock-cushioning structure SA2H. Accordingly, ashock applied to the hard disk 3 can be absorbed by making full use ofthe shock absorption capability of each of the solids SCH, CAH2, andCAL2. Further, the absorbed shock is transferred through entireconnection surfaces of the solids SCH, CAH2, and CAL2. Accordingly, theshock-cushioning structure SA2H can make the full use of its entireshock-absorbing capability, while smoothly cushioning the shock in threephases, thereby reducing the shock applied to the hard disk 3.

It goes without saying that any shock-cushioning structure of thepresent invention can achieve an effect similar to effects achieved bythe shock-cushioning structures SA2 and SA2H described with reference toFIGS. 10 and 11, so long as the shock-cushioning structure is used suchthat its hard material side is in contact with a target object to beprovided with cushioning against shocks, and its soft material side isin contact with a holding means such as a housing. FIG. 12 showsexemplary usage of the shock-cushioning structure SA5 shown in FIG. 8for achieving an effect similar to effects achieved by theshock-cushioning structures SA2 and SA2H.

FIG. 13 shows that the shock-cushioning structures SA described withreference to FIGS. 10, 11, and 12 are provided in a shock-cushioningcontainer C for storing the hard disk 3. As shown in FIG. 13, theshock-cushioning structures SA are provided in four corners of theshock-cushioning container C. Each shock-cushioning structure SAincludes a hard solid CAH provided on the side to be brought intocontact with the hard disk 3, and a soft solid CAL provided on the sidein contact with the shock-cushioning container C. Note that theshock-absorbing container C provided with the shock-cushioningstructures SA as described above accommodates the hard disk 3 whereindicated by two dotted chain lines. The shock-cushioning container Cconfigured as described above is able to smoothly absorb externallyapplied shocks in multiple phases.

As described above, the shock-cushioning structure of the presentinvention can be used for shock protection for a product vulnerable toshocks, e.g., a hard disk drive incorporated in a portable informationapparatus typified by a notebook computer.

While the invention has been described in detail, the foregoingdescription is in all aspects illustrative and not restrictive. It isunderstood that numerous other modifications and variations can bedevised without departing from the scope of the invention.

1. A shock-cushioning structure formed by first and secondshock-cushioning materials which are strained under impact stress toabsorb the impact stress, wherein the first shock-cushioning materialhas a first stress-strain characteristic with a first effectivecushioning stress, and wherein the second shock-cushioning material hasa second stress-strain characteristic with a second effective cushioningstress greater than the first effective cushioning stress of the firststress-strain characteristic.
 2. The shock-cushioning structureaccording to claim 1, wherein the first and second shock-absorbingmaterials and simultaneously undergo the impact stress.
 3. Theshock-cushioning structure according to claim 2, wherein the firstshock-cushioning material has a shape of a solid having a firstprescribed length in a direction along which the impact stress isapplied, wherein the second shock-cushioning material has a shape of asolid having a second prescribed length, which is shorter than the firstprescribed length, in the direction along which the impact stress isapplied, and wherein the first and second shock-cushioning materials areconnected in a connection plane substantially perpendicular to thedirection along which the impact stress is applied.
 4. Theshock-cushioning structure according to claim 2, wherein the firstshock-cushioning material has a wedge-like shape having a planar basesubstantially perpendicular to a direction along which the impact stressis applied, wherein the second shock-cushioning material has awedge-like shape having a planar base substantially perpendicular to thedirection along which the impact stress is applied, and wherein thefirst and second shock-cushioning materials are connected by theirinclined surfaces having a prescribed angle to the planar bases.
 5. Theshock-cushioning structure according to claim 4, wherein the firstshock-cushioning structure is longer than the second shock-cushioningmaterial in the direction along which the impact stress is applied. 6.The shock-cushioning structure according to claim 4, wherein theinclined surface of the first shock-cushioning material is convex andcurved, and wherein the inclined surface of the second shock-cushioningmaterial is concave and curved.
 7. The shock-cushioning structureaccording to claim 1, wherein the first shock-cushioning materialundergoes the impact stress before the second shock-cushioning materialdoes.
 8. The shock-cushioning structure according to claim 7, whereinthe first shock-cushioning material has a shape of a solid having afirst prescribed length in a direction along which the impact stress isapplied; wherein the second shock-cushioning material has a shape of asolid having a second prescribed length, which is shorter than the firstprescribed length, in the direction along which the impact stress isapplied, and wherein the first and second shock-cushioning materials areconnected in a connection plane substantially parallel to the directionalong which the impact stress is applied.
 9. The shock-cushioningstructure according to claim 8, wherein the first shock-cushioningmaterial has a shape of a cube, and wherein the second shock-cushioningmaterial has a concave and curved surface for receiving the impactstrain.
 10. The shock-cushioning structure according to claim 3, whereinthe first shock-cushioning material has a surface which is opposed toand smaller than the connection surface, and wherein the secondshock-cushioning material has a surface which is opposed to and smallerthan the connection surface.